Fibrinogen is a very important coagulation factor which acts in the final stage of the blood coagulation cascade. Fibrinogen, e.g. upon activation of the coagulation system after an injury, is converted by thrombin from its soluble form into insoluble fibrin which plays an important role in hemostasis and wound healing.
Fibrinogen has importance in hemostasis and wound healing. For instance, fibrinogen has been used clinically as an intravenous dosage form in a replacement therapy against congenital and acquired fibrinogen deficiencies etc. to hamper a serious bleeding by increasing the fibrinogen level in blood. Additionally, in recent years, fibrinogen in admixture with thrombin is used in a surgery as an adhesive for substitute of suture of soft organs such as the liver and the spleen or as an auxiliary agent for the suture. Fibrinogen has also widely been applied in other clinical set-up.
Such a preparation, capable of adhering to a wound or a tissue surface, may enhance a tension strength of an adhesion site or a joined wound, may fully be absorbed within the living body and may promote the healing of wound.
As described in Patent reference 1, a method of the preparation of a tissue adhesive comprising fibrinogen and blood coagulation factor XIII (Factor XIII) is known. Factor XIII is activated by thrombin in the presence of calcium ion (activated Factor XIII). The activated Factor XIII forms a cross-link of isopeptide linkage between fibrin molecules, i.e. γ dimer, to thereby increase physical strength and stability of the fibrin clot. Therefore, the fibrin adhesive used widely as a tissue adhesive comprises a substantively necessary amount of Factor XIII irrespective of whether said Factor XIII is externally added as a purified Factor XIII or contained as a contaminant of materials while preparation of fibrinogen. The term “a substantively necessary amount of Factor XIII” as used herein refers to a concentration resulting in γ dimer (non-Patent reference 1).
A tissue adhesive is not stable in a form of a solution and thus is used in clinical practice in a dosage form of a frozen solution or a lyophilized powder. Therefore, a commercially available preparation has to be thawed or rehydrated before application, in either of which a lot of time is wasted.
Additionally, to obtain a sufficient adhesive action as a fibrin adhesive, it is necessary to dissolve fibrinogen in a high concentration. The higher the concentration of fibrinogen to be coagulated is, the more favorable. However, there was a problem that such a high-concentration fibrinogen solution is not suitable for use in a surgery of urgency since it takes a long time to make the solution from a lyophilized fibrinogen preparation. It is concerned that a prolonged preparation including dissolution of a lyophilized fibrinogen may adversely affect a patient.
Moreover, when a fibrinogen solution is prepared in a high concentration, rehydration of a lyophilized powder tends to result in bubbling. After the rehydration, the resulting fibrinogen solution is transferred into an applicator such as a syringe, but due to the bubbling, the preparation-time is further prolonged. Therefore, a preparation with an improved defoaming property is desired in a clinical practice.
Thus, medical doctors demand that the time for preparation is shortened because a quick availability is critically important especially at emergency including surgical procedure.
For the reasons described above, many attempts have been done to obtain a lyophilized product which has an improved rehydration time. For example, Patent reference 2 describes a method and procedure of improving the solubility of a lyophilized medicine by using an apparatus in combination with heating and stirring, which however is still insufficient for an improved rehydration time.
It is known that the solubility of a poorly soluble protein may be improved by addition of a certain additives. For example, Patent reference 3 discloses a lyophilized fibrinogen composition containing urea or a substance with a guanidine residue. Also, Patent reference 4 discloses a lyophilized fibrinogen composition containing at least one biologically compatible surfactant. However, in any commercially available preparations manufactured by any methods, it takes a lot of time to rehydrate a lyophilized powder and hence further improvement in the dissolution time is desired.    Patent reference 1: Japanese Patent Publication No. 63-40546    Patent reference 2: Canadian Patent 1,182,444    Patent reference 3: Japanese Patent Publication No. 4-7328    Patent reference 4: Japanese Patent Publication No. 2-36872    Non-patent reference 1: Dickneite, G., et al., Pharma Medica 21(9), p. 105-118 (2003)